Flying Papercraft.com Flying your Papercraft Plane Photo: Tie Brooks Tie Photo: Flying Papercraft.com THE ABOVE SEA LEVEL DIVISION OF BROOKS BOATS DESIGNS Pg. 1 Flying Papercraft.com A-4 Contents Flight Characteristics .............................2 Learning to Fly ..........................................2 Forces on a Plane .....................................3 Center of Gravity .....................................4 Control Surfaces ......................................5 Washout Bend ....................................................................6 Flaps .......................................................................................6 Leading Edge Flaps ..........................................................6 Elevators ...............................................................................7 Ailerons .................................................................................7 Rudders .................................................................................7 First Flight ...................................................8 Preflight Check ..................................................................8 Setting Up for Slow Flight .............................................8 Adjusting the Plane ..........................................................9 High Speed Flight ...........................................................10 Scale ....................................................................................10 Fun Things to Do With Your Plane ...11 Turns ....................................................................................11 Rolls ......................................................................................11 Landing ...............................................................................12 Loops ...................................................................................12 High Flying ........................................................................12 Flying in Wind ...................................................................12 A Final Thought ...............................................................13 All photos are by Leigh, Tie, Hanxiang and Jack Brooks, except where noted. Thanks guys!! Copyright Ⓒ 2014 John Brooks All rights reserved. Pg. 2 Flying Papercraft.com A-4 Flying your Papercraft plane Flight Characteristics You built the plane out of card stock so it is heavy. However, your plane can be thrown quite hard, so it can go fast, high and far. And because it is heavy, your plane can fly in much more wind than many l planes made out of regular paper. In fact, it can be quite fun to fly in some wind. Here is how your plane can fly: A flying version of a regional jet. When I first test a plane I am usually inside the house where there are two rooms connected to make a space that is a little over 30 feet (10 meters) long The planes usually hit the opposite wall with a resound thwack at about the same altitude they left my hand. In the back yard‒an average sized back yard‒the plane often ends up on the roof or in the surrounding bushes. So we often fly on the soccer field at school and occasionally can use up nearly all the airspace over half the field! With some adjusting and practice, you can make this little plane really fly! Learning to fly The model used to illustrate this manual is the A-4 Skyhawk. You have built a sophisticated flying machine. While all planes are influenced by the same forces as they move through the air, and all paper planes can be adjusted for where they go, on this plane you can change the shape of the wings for different speeds you want to fly, and there are many ways to adjust how and where your plane flies. Along with learning how the plane flies, you will also be learning just how to throw it so it will go where you want. A gentle take off is a good idea for the first flights.. Pg. 3 Flying Papercraft.com A-4 Forces on a plane How a plane glides takes a little explaining. The wings The first thing to understand is the four primary and the horizontal tails on your plane create an area forces working on a plane as it flies. of lift and somewhere in those areas is the Center of Lift, a point where the amount of lift in front of that The two forces that keep the plane in the air are lift point is the same as the amount of lift behind it. on the wings and thrust when you throw it. The two forces that eventually bring the plane back to the At the same time, the weight of your plane is ground are gravity, and drag, which slows the plane centered around a point called the Center of Gravity as it pushes through the air. The center of lift is the force going up, the center of For a wing to create lift, it has to be moving through gravity is force going down. For a plane to glide, you the air. And the faster the wing is moving, the more need the center of gravity in front of the center of lift that is created. The amount of lift created also lift so the nose tips down and air flows over the depends on amount of section shape in the wing. wings. How far apart or close together the two points are is the balance of the airplane. If you took an airplane and sawed through the wing parallel to the centerline of the plane, then looked at The center of lift is complicated because on a foil the cut end, this is the wing section. The more shape shape (the section of wing) the center of lift is not in there is in the this section, the more lift it creates the middle, but instead is about 1/3 of the way back and the slower the plane can fly. Jet fighters are from the leading edge of the wings and horizontal designed to go fast so their wing sections are pretty tails. flat and thin. Gliders are designed to go slow so their What that tells us is that we want the center of wing sections are thick and well rounded. gravity pretty far forward on the wings, as you will see as we talk about finding the center of gravity of All wing shapes have a point at which the air speed is your plane. too slow to create any lift and the airplane simply falls out of the sky.This point is ominously called the stall speed. A stall in a car means it can’t go. In a plane it means it can’t fly. I am sure you have flown a paper plane and watched as it goes up, then drops, goes up, then drops again. What is happening is, as the plane rises, it losses speed to drag and gravity, until the wings stall, then the plane’s nose (which is heavy) drops, gravity speeds the plane up, the wings create lift, the nose rises until the wings either stall again or the plane glides to the ground. Forces on a plane are pretty easy to understand, but how they interact with a plane can get very very complex and you can study it for many years to come. Let’s get back to flying your new plane. One thing to understand is the balance of your plane. Your plane is a glider. That means that after Circles under the wings of the A-4 is the location of you throw it, there is no engine to provide thrust and the Center of Gravity. so your plane just . glides. Pg. 4 Flying Papercraft.com A-4 Center of Gravity Planes are sensitive to where the center of gravity is located and although your plane has been adjusted for a good flight, you may need to adjust it to make your plane fly better. To find the center of gravity (CG), use your thumb and middle finger to balance the plane under the wings. Move the plane forward or aft until it sits level. Where your fingers are touching the plane is the center of gravity. The pictures show a model of the A-4 and it flies best if the CG is at a point within the circles on the underside of the wings. If the CG is forward of this, Balancing the plane to find the center of gravity. the plane needs much more elevator to fly level and it will fly slow and only for a short distance. If it is aft of this point, it will nose up very easily and stall, then it A quick and temporary way to add weight is by putting can nose dive to the ground. small pieces of blue painters masking tape on the nose or tail. If you don’t like the change, take the tape off. If To move the CG aft, glue the tail weights to the you do, replace the tape with card stock weights underside of the tail cone. To move the CG forward, glue nose weights to the bottom of the fuselage and When you have flown the plane for awhile, you may nose cone. find that you want to make small adjustments to the CG to get better glides by moving the CG forward, or Add the weights gradually, one at a time, then try get more maneuverability by moving the CG aft. If you some flights to see how the plane flies. Small changes like to fly in some wind, moving the CG forward can make a big difference. Add more as you need. help make the plane fly better. Tail weights are glued on the horizontal tail to adjust the CG towards the back of the plane. Gluing on a nose weight to adjust the CG towards the front of the plane. Pg. 5 Flying Papercraft.com A-4 Control Surfaces There are four control surfaces on your plane, three that make the plane fly where you want it to go, and one that changes the shape of the wings for different flight speeds. The drawing shows where these control surfaces are on most planes, including your regional jet. The three steering control surfaces are: Elevators on the horizontal tails control how much the nose points up or down. You’ll adjust these the most. Ailerons, the smaller movable tabs on trailing edge Cut the lines for the various control surfaces after the plane is fully assembled. of the wings, at the tips, control the plane’s roll or banking. Control Surface Bends Rudder on the vertical tail is used sparingly for turns. The fold lines for control surfaces are not scored The wing shape control is: because the bends are not permanent‒ we want to be able to change them.